Air turbine handpiece

ABSTRACT

An air turbine handpiece having: a head portion with built-in free turbine blade, a neck portion installed consecutively with the head portion and grasped by an operator, a grip portion installed consecutively with the neck portion, an air supply duct for driving the turbine blade, and an exhaust duct for exhausting the air. The exhaust duct is provided with a reflux duct, open at one end to the exhaust duct, and open at the other end to the turbine room as the exhaust exit, a value in which an aperture at the reflux exit of the reflux duct is divided by an aperture in the air supply port of the air supply duct, becomes one or less, and the reflux exit of the reflux duct is opened to the turbine room near the air supply port between the air supply port and the exhaust exit.

TECHNICAL FIELD

The present invention relates to an air turbine handpiece used fordental therapeutics etc., particularly, an air turbine handpiece capableof improving the rotation efficiency of the turbine, in which when theturbine stops in case of ending use of the kind of air turbinehandpiece, generation of negative pressure due to inertia rotation ofthe turbine blade is prevented in the turbine room and the reflux ductas a negative pressure prevention means is used as the promotion meansof driving force at the time of driving the turbine again.

BACKGROUND ART

When the drive of the turbine is ended, the conventional air turbinehandpiece intercepts the supply of the pressurizing air being as drivingmedium. However, even if the supply of the pressurized air isintercepted, the turbine blade continues the inertia rotation by owninertia force so that the air in the turbine room is exhausted by theinertia rotation, resulting in a generation of negative pressuretherein. Moreover, the air in the turbine room is communicated withambient air through the gap in surroundings of rotation axis so thatinterior of the turbine room becomes a negative pressure, resulting ingeneration of negative pressure in the turbine room. Moreover, the airin the turbine room is communicated with the ambient air through the gapin surroundings of rotation axis, so that the interior of the turbineroom becomes a negative pressure, resulting in a inhalation of ambientair in the turbine room, and resulting in a inhalation of contaminantsuch as saliva and blood etc. of patient together with the inhalation ofambient air. As a result, the interiors of the joint metal fittings andthe feed and exhaust hoses which are connected to the interior of thehead portion and/or the handpiece, are polluted. In this way, when theinterior of the handpiece is polluted, the cross infection mightgenerate through the handpiece between the patient and the operator oramong patients, so that in order to improve this problem, varioustechniques have been developed before, for example, the inventions ofpatent documents 1 to 7 are well-known as stated below.

The invention of the patent document 1 comprises a feed duct thatsupplies the compressed air from the compressed air source to the airturbine, and an exhaust duct for performing the exhaust, characterisedin that the feed valve is provided to the feed duct, the exhaust valveis installed to the exhaust duct, the feed valve and the exhaust valveare closed at the end of driving of the handpiece at the same time, atthe end of driving or after closing the exhaust valve, the air supplyvalve is closed, it is obstructed that the negative pressure generatesin the handpiece, and the contaminant is prevented from being inhaled inthe handpiece.

The invention of the patent document 2 comprises a turbine wheelaccommodated rotatably to the inner space portion formed to the headportion of the handpiece, an air inlet for supplying air toward theturbine wheel, and an exhaust vent for exhausting air supplied to theturbine wheel, one or plurality of buffer spaces for feeding and storingair with centrifugal force given by rotation of the turbine wheel, inthe pressurized condition, a path for discharging the dissolved airstored in the buffer space in the atmosphere from surroundings of thetool to rotate with the turbine wheel, and a sidewall portion existingbetween the turbine wheel and the exhaust vent, and positioned at thesurrounding direction in order to give resister to the air moved fromthe turbine wheel to the exhaust vent, and thus the buffer space isopposed to the rotation direction of the vane.

Moreover, according to the handpiece of this constitution, even if thedrive of the handpiece is ended and the charge is stopped, the air inthe turbine room is exhausted by the inertia rotation of the turbinewheel, but the flow of air moved from the turbine wheel toward theexhaust port is obstructed by the sidewall portion that intervenesbetween the turbine wheel and the exhaust port, and the air rotatedtogether with the turbine wheel is stored in the pressurized conditionin the buffer space formed at the outer side of the turbine wheel basedon the centrifugal force provided for air. Furthermore, the stored airis emitted from the surrounding of the tool in the atmosphere, throughthe air duct formed to the head portion, so that the prevention of thesack back can be enabled.

The invention of patent document 3 comprises a means for preventing thepressure medium rotated in the turbine room, from being emitted throughthe exhaust duct, during the inertia rotation of the bladed wheel of theturbine after the supply of the pressure medium is stopped.Particularly, in the handpiece for the medical treatment or dentistry,the above means is mounted to the region of the turbine room, in thefunctional operation, the pressure medium rotated in the turbine room isinclined beyond the outlet opening, and has a flow Web for forming aflow stepped portion for the pressure medium rotated by the above means,so that the pumping function, inhalation and retraction are prevented.Also, an intermediate web is located on the transversal plain ofintermediate of the bladed wheel of the turbine substantially, as aresult, the inlet opening portion is mounted to fit togethersubstantially with the inlet channel existed between the intermediateweb and the related sidewall portions of the turbine room, and anintermediate web is extended to the convergence direction or obliquedirection, with respect of inflow direction, in the condition that apoint of a round web is directed to the rotating direction, so that thepower of the turbine can be increased.

The invention of patent document 4 disclose a manual dental apparatuscomprising an air passage for supplying driven air to the turbine anexhaust air passage connected directly to a cylindrical surface of theturbine room, and for exhausting the air driven from the turbine room,characterised in that the exhaust air passage is opened to the regionbetween the rotor and the bearing at tool side and near the axis of theturbine room through the connection passage, or the exhaust air passageis opened to a cylindrical wall of accommodation hole of the head wallthrough the connection passage, at the tool side in the bearing providedto the tool side, or the exhaust air passage is opened to the region ofthe axis near of the turbine room, and/or the hollow room of the tooloperation mechanism at the opposite side of the tool side of the rotornear through the connection passage, so that It is prevented the ambientair from being inhaled with the negative pressure generated by theinertia rotation of the rotor, in such a manner that the connectionpassage connected to the exhaust air passage is opened to the regionaround the axis.

The invention of patent document 5 is characterized in that as anembodiment 1 the chamber of the head portion is provided with a nozzleopening for spouting air to the turbine blade portion of the aboverotor, and an exhaust port for exhausting the gushed air outside, thewidth W of the above arc shaped nozzle opening along the direction ofthe circumference of the turbine blade portion is set to twice or moreheight H in the direction of the rotation axis of the rotor.

And, in this handpiece, a circular arc width W in the circumferentialdirection of the nozzle opening for jetting air toward the turbine bladeportion is set to twice or more height H in the direction of therotation axis, and, the nozzle opening is made in long circumferentialshape, so that the air jetted from the nozzle opening intensivelyoperates to the central portion in the axis direction of the turbineblade of the turbine blade portion, the area of the nozzle opening isalso large, the amount of air supplying is also large, and the rotor canbe rotated and driven efficiently with high torque.

Moreover, the invention of this patent document 5, as second embodiment,comprises a rotor arranged to the head portion in the chamber formed ina head portion, supported rotatably through the bearing means with therotation axis integrally, and having tool mounted detachably, theturbine blade portion of the above rotor includes a hub portion and aplurality of turbine blades that essentially put equal intervals on theouter peripheral surface of the hub portion circumferentially, the airturbine handpiece comprises respective turbine blades including a firstblade portion essentially extended convexly in a circular arc shape, inthe above rotor rotating direction, and a second blade portion extendingbehind the rotating direction of the above rotor toward a direction awayfrom the first blade portion and serially extending essentially to thefirst blade portion, the above chamber is provided with a nozzle openingfor gushing the air toward the above first blade portion of the aboveturbine blade, and an exhaust opening for exhausting the air gushedtoward the above turbine blade outside, the outer peripheral surface ofthe above hub portion extends inside in radial direction, in thecircular arc shape, concavity toward the lower end from the upper end,the air gushed from the above nozzle opening to the first blade portionof the above turbine blade, is guided by the above first blade portion,flows behind the above rotating direction, is guided by the above secondblade portion and is led downward toward and behind the above rotatingdirection toward a direction away from the above first blade portion,and afterwards is exhausted outside through the exhaust opening.

And, the handpiece of this construction comprises first blade portionthat extends in rotor rotating direction by respective turbine blade ofthe rotor and essentially extends convexly in the circular arc shape,and second blade portion that essentially continues from the first bladeportion, and extends behind above in rotating direction in awaydirection therefrom, the air from the nozzle opening is jetted towardthe first blade portion of the turbine blade. Therefore, the air jettedfrom the nozzle opening flows behind the rotating direction along thecircular arc plane of the first blade portion, further, is led to therotating direction along the second blade portion following the firstblade portion, the flow of the air that flows along the turbine bladebecomes smooth. Thus, the air jetted toward the turbine blade portionflows smoothly along the turbine blade and hardly operates as arotational resistance, and thus the rotor can efficiently be rotated anddriven. Also, in this invention, the outer peripheral surface of theabove hub portion extends inside in radial direction, in the circulararc shape, concavity toward the lower end from the upper end, so thatthe air from the nozzle opening operates to the hub portion, and canraise the rotor rotating torque.

Furthermore, as an embodiment 3 of the invention of patent document 5,the outer peripheral surface of the first portion being the upperportion of the above hub portion extends inside in radial direction, inthe circular arc shape, concavity toward the lower end from the upperend, and the outer peripheral surface of the second portion being thelower side of the hub portion extends under the rotation axis directionof the above rotor. Also, this invention is characterized in that a partof air gushed from the above nozzle opening is led to the above turbineblade, after guiding it by the above first and second portions of theabove hub portion. And, the handpiece of this constitution includes afirst portion that the hub portion of the turbine blade essentiallyextends in the circular arc shaped toward the inside of the rotorradial, and a second portion that extends from the first portion to therotor rotating direction, so that a part that operates to the hubportion of the air jetted from the nozzle opening, is led to the turbineblade along the second portion from the first portion, and operates tothe turbine blade, and thus the rotor rotating torque rises.

The invention of the patent document 6 characterized in that theaperture of the exhaust vent at the inlet end of the exhaust passage isset large to the aperture of the air supply vent at the tip of thecharging passage, and the air passage circling around in the housing andfrom the above air supply vent to the above exhaust vent, is madeenlarge from the air supply vent to the exhaust vent side sequentially,further, the above turbine blade is assumed the top and bottom twoconnecting systems with same rotation axis, a separator is providedbetween two turbines, and chamber inside of the hub portion and chargingpassage, exhaust passage, and air passage of neck portion are dividedinto two systems according to respective turbines. Moreover, in additionto the above constitution, the space between the turbine blade and upperand lower internal wall surface of the chamber is made narrow,particularly, an increase in the torque that caused to rotate thecutting tool.

In the above description, as for the first turbine blade and the secondturbine blade, in view of the axial direction of the rotation axis, anupper and lower interval between the turbine blade and the upper andlower internal wall surfaces of the top and bottom of the chamber, istaken narrow, so that it prevent the pressurized air jetted to theturbine blade from being spread rapidly by the gap at the above upperand lower intervals, and thus prevent the speed of the charging frombeing decreased. Also, for the aperture of the air supply vent of thecharging passage, the aperture of the exhaust vent that circles aroundin the chamber of the head housing and exhausts air, is set large, theair passage from the above air supply vent to the exhaust vent has across-sectional area which is increased sequentially, from the airsupply vent in the tip of the charging passage, and then fitted in theaperture of the exhaust passage at the exhaust vent, also, right andleft intervals between a right and left outer periphery internal wallsurface in the chamber and the tip of respective turbine blades, aremade in such a manner that its radius of curvature is enlargedsequentially from the air supply vent to the exhaust vent.

In the handpiece of this constitution, the interior of the chamber iscircled around clockwise in view of the above of head portion along theinternal surface, and is exhausted, after rotating the turbine bladewith shocking pressure of the pressurized air jetted from the air supplyvent, at this time, the volume of the chamber being as the ventilationpassage is enlarged sequentially from a starting point of the air supplyvent, so that it prevents a generation of the resistor operation thatdecrease the air supplying speed and preclude the rotation of theturbine blade without rapidly spreading the pressurized air. Further, inthe exhaust vent, the volume of the exhaust is made identical with theexhaust passage, so that the flow of the pressurized air which circlearound the interior of the chamber in the process of charging andexhausting, arrives at the exhaust vent with same aperture as theexhaust passage of the enlarged part in the chamber sequentially, andthus air density lowers sequentially, and then it can prevent theresistor operation that decreases the rotation of the turbine blade.

Further, it is assumed the connecting system of the first turbine bladeand the second turbine blade, the rotation axis is assumed to beidentical, and then the power of the torque is made double by the samerotational frequency. Also, the air supply and the exhaust system aredivided into upper and lower two corresponding to the top and bottom twoturbines, thereby reducing the damage in the air supply. Therefore, theaxial side separator and the housing side separator are provided betweenupper and lower turbine blades, for the above-mentioned operation, theefficiency of the turbine improves large, and the torque of the rotatingcutting tool can be increased.

The invention of the patent document 7 provides a rotor of the dentalair turbine handpiece, this rotor is vertical to the rotation axis, andhas the flywheel with a thickness that the air receiving band positionedat surroundings of the rotor blade is divided equally, the position ofthe flywheel may take a high position or a low position, but preferablymay takes an intermediate position, and then when the intermediateposition is taken, the promotion of the rotor is efficient further.Moreover, when the vertical plane of respective wedged shaped bands ofthe upper train, is overlapped regularly for the vertical plane ofrespective wedged shaped bands of the under train, It is increased thepulse formula of the rotor air for each turn, and enabled an increase atthe starting speed and the maintenance of the torque in the state of thehigh revolution. It may shift the overlapping of the vertical plane ofrespective wedged shaped bands of the lower train only by a half bandconcerning the vertical plane of respective wedged shaped bands of theunder train. Also, though the air discharging jet can utilize only byone, in order to elevate efficiency, usually one air jet is divided into2 or plurality of jets with equal diameter or small diameter, thearrival of the pressurized air to a unified air receiving band withwedged shape is efficiently concentrated, and thus an increase at thestarting speed and the maintenance of the torque in the state of highrevolution, become possible.

PRIOR ART DOCUMENTS

Patent documents:

Patent document 1: JP, H06-047060, A

Patent document 2: WO2006/101133 gazette

Patent document 3: JP4100833

Patent document 4: JP3907284

Patent document 5: JP3208345

Patent document 6: JP3684643

Patent document 7: JP, H01-104254, A

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

However, the above patent documents 1-7 have the following problems. Inthe case of the above patent document 1, the feed valve and the airrelease valve must be provided, and electric signal for operating theexhaust valve (the electric signal for operating solenoid-controlledvalve)or the air signal (the air signal for operating the air valve)must be needed. Also, in order to operate the above circuit moreeffectively, after shutting the exhaust valve, it should be operated toshut the air supply valve, the control circuit operated in this orderbecomes indispensable. Additionally, the addition of the component andthe circuit is necessary, and it becomes the cost up. Furthermore, thiscircuit is applied to the product newly shipped by the factory, andthere is a problem that it is not easy to correspond to the conventionalproduct of the market.

In the case of the patent document 2, it necessary to provide an airsupply vent for supplying air to the turbine wheel in head portion ofhandpiece, an exhaust vent of the supplied air, a buffer space foraccepting and storing in pressurized condition, the air imparted thecentrifugal force by rotating the turbine wheel in the head portion, anda circumferential shaped sidewall portion imparted resistor to airflowed from the turbine wheel to the exhaust vent, and positionedbetween the turbine wheels and exhaust head. And, in order to producethe effect effectively, the buffer space is opened oppositely in therotating direction of the turbine wheel, resulting in a prevention ofthe sack buck, so that the structure complicates and is complex, andthus it becomes cost up.

In the case of the patent document 3, the outlet opening portion placedat the region of the turbine room, the flow recess connected with theoutlet opening portion, and the machining of Web, are complex and it isbecoming the cost up. And, as for the arrangement of a middle webpositioned substantially at the transversal planar of intermediate ofthe bladed wheel of turbine, and an inlet opening portion or the relatedsidewall portion of turbine room, the round web tip of the intermediateweb is extended to the convergence direction or oblique for the inflowdirection in the state directed to the direction of the rotation,thereby increasing the power of the turbine, but this is a thought thatthe positional relation between the shape of middle web and the passageconnected with the inlet opening portion and the outlet opening portion,makes a smooth flow and thus it is effective, but the extent of“increase of power” is not shown. Moreover, it becomes a very complexmachining and becomes further cost up that the intermediate Web of thebladed wheel of turbine is provided.

In the case of the patent document 4, there is not easy the machining ofthe connection passage opened in the region around the axis and iscommunicated with the exhaust air passage, and there is a problem ofbecoming the cost up as described above. Moreover, though the presentinvention is a similar constitution to the invention of the presentapplication, it is different from the invention of the presentapplication, the connection passage communicated with the effluent airpassage is opened to the region around the axle etc. remote from thenegative pressure generation portion of the turbine room, the generationof the negative pressure is not inhibited directly, the influence of thegenerated negative pressure is relaxed, moreover, the processing cost isbulky from constructional and thus it is a quite different constitutionfrom the present invention.

The embodiment 1 of the patent document 5 intends the rotor to rotateand drive with the high torque by efficiently applying the air (in theflow direction) gushed toward the turbine blade portion of the rotor toplural turbine blades, however, the width W of the nozzle opening forgushing the air toward the turbine blade portion must be set to twice ormore height H in the direction of the rotation axis line of the rotor,opening portion of usual nozzle diameter 1.0 mm to 1.5 mm extent is madewidened to twice or more the above height H (usually 3.0 mm to 3.5 mmextent), so that the machining is not easy, and thus there is a problemof becoming the cost up similarly to the above.

In the second embodiment, the air jetted from the nozzle opening flowsbehind the rotating direction along the circular arc plane of the firstblade portion, it is led in the direction of the rotation along thesecond blade portion following the first blade portion, and flows alongthe turbine wing so that the flow of the air becomes smooth. Thus, theair jetted to the turbine blade portion flows smoothly along the turbineblade, and it hardly operates as a rotational resistance, so that therotor can be efficiently rotated and driven. Moreover, the outerperipheral surface of the above hub portion extends inside in radialdirection, in the circular arc shape, concavity toward the lower endfrom the upper end, so that the air from the nozzle opening operates tothe hub portion, and can raise the rotor rotating torque. Such a shapeof rotor (consisting of respective turbine blades) is constructed by thethree-dimensional (substantial third-dimensional) machining, so that thecomplexity of the machining and the machining programming of the rotoris hard to describe. Further, it is easy to imagine that a lot ofmachining time is spent, and becomes the big cost up.

According to the third embodiment, a part where the operation works tothe hub portion, of the air jetted from the nozzle opening, is led tothe turbine blade along the second part from the first part the, andoperates to the turbine blade and thus contributes to the rotor rotatingtorque, so that the rotor rotating torque can be raised. In this case,the shape of the rotor consisting of a respective turbine blade not onlyhas a three-dimensional (substantial three-dimensional) shape in thesame way as the above, but also, has constituted from the turbine bladegroup in two upper and lower stages, and then the lower step becomeslike the minor diameter of screw (substantial reverse-cone), so that themachining and the machining programming of the rotor is hard todescribe. Furthermore, it is easy to imagine that a lot of machiningtimes are spent, and it becomes the big cost up.

In the case of the patent document 6, the exhaust passage should bemachined so as to expand the curvature radius sequentially from the airsupply vent and to arrive at the exhaust vent, and while decenteringsequentially the inner wall (chamber) of almost cylindrical shaped headagainst the center of the head (rotor rotation axis), the exhaustpassage should be formed, it is clear that the machining is complexcompared with the invention of the present application. Furthermore, inthe case that the first turbine wing and the second turbine wing aremade as the connecting system, it proposes to divide the charging airsystem and the exhaust system into upper and lower two, corresponding tothe top and bottom two turbines, and thus an addition of the exhaustsystem is to increase the machining number of man-hours, and it becomesthe cost up.

In the case of patent document 7, the main subject of the invention isthe matter that an increase at the starting speed and maintenance of thetorque in the state of the high revolution are possible, and so-called“Flywheel” was incorporated in a part of the rotor. Thus, this isdifferent from the matter that the rotation driving force of the airturbine handpiece of the present application is enhanced, and theenergy-saving effectiveness is effected.

Therefore, the present invention was developed to provide the airturbine handpiece by considering the problems in the above patentdocuments 1 to 7, in such a manner that even if the air charge isstopped at the turbine-drive ending of the handpiece, the turbine bladeis effected to drive with the inertia rotation, so that in order toprevent the negative pressure from being generated in the turbine room,the negative pressure prevention means is provided to reflux the exhaustto the turbine room, and the exhaust is refluxed to the turbine roomduring the usual turbine-drive other than at the time of the negativepressure prevention, at the same time, the rotation driving force of theturbine blade can be enhanced, by jetting the reflux exhaust stream inthe above negative pressure prevention means together with the aircharge jetted toward the turbine blade.

That is, the present applicant has proposed the invention previously inPatent Application No. 2010-211589, in order to resolve the problem thateven if the air charge for driving the turbine is stopped, the negativepressure is caused in the turbine room by the inertia rotation of theturbine blade, and the contaminant of saliva and blood etc. of thepatient are inhaled in the head portion by the negative pressuretogether with the ambient air, we prevented the negative pressure frombeing generated in the above turbine room, and in the time of drivingthe turbine commonly, the rotation driving force of the turbine ispromoted, and the secondary effect for reinforcing the rotation drivingforce of the turbine blade can be obtained. Therefore, afterwards, thepresent inventor advances a development further in relation to theimplement of the above invention, as the result of the fact that thereflux duct of the exhaust as being the above negative pressureprevention means may be utilized positively as a rotation driving forceof the turbine blade, the exhaust after the turbine-drive is refluxed tothe turbine room through the reflux duct of the above negative pressureprevention means, at the same time, the air charge is jetted to theturbine blade, as a result, the present inventor confirmed the fact thatthe driving force was able to be improved remarkably.

SUMMARY OF THE INVENTION

The invention of claim 1 according to the present invention is an airturbine handpiece comprising a head portion forming therein a turbineroom, in which a rotatable turbine blade is provided; a neck portioninstalled consecutively with the head portion and grasped by anoperator; a grip portion installed consecutively with the neck portionbehind thereof; an air supply duct for charging air from an air supplyport to drive the turbine blade; and an exhaust duct for exhausting theair from the exhaust vent after rotating the turbine blade by thecharged air; characterised in that the exhaust duct is provided with areflux duct for the exhausting, one end of the reflux dust is opened tothe exhaust dust as an reflux entry, and the other end of the refluxdust is opened to the turbine dust as the exhaust exit.

The invention of claim 2 according to the present invention is an airturbine handpiece as claimed in claim 1, charecterised in that thereflux duct is constituted in such a manner that a value in which anaperture at the reflux exit of the reflux duct is divided by an aperturein the air supply port of the air supply duct, becomes one or less, andthe reflux exit of the reflux duct is opened to the turbine room nearthe air supply port between the air supply port and the exhaust exit.

The invention of claim 3 according to the present invention is an airturbine handpiece as claimed in claim 1, charecterised in that thereflux duct is constituted in such a manner that when the aperture inthe air supply port of the air supply duct is assumed to be D0, and theaperture at the reflux exit is assumed to be D1, the aperture at thereflux exit of the reflux duct is set as D0:D1=1:0.62 to 0.92, and thereflux exit of the reflux duct is opened to the turbine room near theair supply port between the air supply port and the exhaust exit.

The invention of claim 4 according to the present invention is an airturbine handpiece as claimed in claim 3, charecterised in that thereflux duct is constituted in such a manner that when the aperture inthe air supply port of the air supply duct is assumed to be D0, and theaperture at the reflux exit is assumed to be D1, the aperture at thereflux exit of the reflux duct is set as D0:D1=1:0.77, and the refluxexit of the reflux duct is opened to the turbine room near the airsupply port between the air supply port and the exhaust exit.

The invention of claim 5 according to the present invention is an airturbine handpiece as claimed in any one of claims 1 to 4, charecterisedin that the reflux duct is installed consecutively with another refluxduct through the reflux entrance for exhausting opened to the exhausttube, and the reflux exit of the reflux duct is opened to the turbineroom of the air supply port near in the tip of the nozzle installedconsecutively to the exit side of the air supply duct.

The invention of claim 6 according to the present invention is an airturbine handpiece comprising a head portion forming therein a turbineroom, in which a rotatable turbine blade is provided; a neck portioninstalled consecutively with the head portion and grasped by anoperator; a grip portion installed consecutively with the neck portionbehind thereof; an air supply duct for charging air from an air supplyport to drive the turbine blade; and an exhaust duct for exhausting theair from the exhaust port after rotating the turbine blade by thecharged air; characterised in that the air supply duct is installconsecutively with a nozzle, and the exhaust duct is provided with areflux duct, one end of the reflux duct is opened to the exhaust duct asan reflux entry, and the other end of the reflux duct is opened to nearthe air supply port of the nozzle as an exhaust exit.

EFFECT OF THE INVENTION

In the air turbine handpiece according to the present invention, one endof the reflux duct is communicate with the exhaust tube and the otherend of the reflux duct is opened to the turbine room near the air supplyport of the air supply duct, so that the exhaust is returned directly tothe portion where the negative pressures are caused easily most in theturbine room, and the negative pressure can be prevented from beinggenerated efficiently by the refluxed exhaust. As a result, the foreignmaterial can be prevented from being inhaled in the handpiece when thenegative pressure is generated in the air turbine handpiece, and thecross infection between patient and operator or among patients can beprevented from being generated through the air turbine handpiece. Also,in the air turbine handpiece according to the present invention, thereflux duct communicated with the exhaust duct is provided near the airsupply port of the air supply duct, and the exhaust is returned directlyto the portion of the turbine room where the negative pressures arecaused most in turbine room, so that the negative pressure can beprevented from being generated by the refluxed exhaust. Furthermore, inthe case of using the air turbine handpiece, the reflux air suppliedfrom the reflux duct is jetted toward the turbine blade together withthe supplied air of the original driving force, so that the secondaryeffect that the rotation drive of the turbine blade can be helped, canalso be obtained. Moreover, the constitution of the reflux duct issimple, and the machining is also easy, so that the air turbinehandpiece can be provided with low price. As a result, present inventionhas an advantage that the cross infection between patient and operatoror among patients can be prevented from being generated through theconventional air turbine handpiece. Particularly, also, according to thepresent invention, a value in which an aperture at the reflux exit ofthe reflux duct is divided by an aperture in the air supply port of theair supply duct, is set to one or less (≧1), so that during use of theair turbine handpiece, in addition to the air charge jetted from the airsupply duct toward the turbine blade, the supply quantity of airincreases by the reflux exhaust supplied to the negative pressuregeneration portion of turbine room through the reflux duct, and thus therotation driving force of the air turbine handpiece is reinforced andthe energy-saving effect can be obtained. Moreover, the constitution ofthe reflux duct according to the present invention is simple, and themachining is easy, so that the air turbine handpiece can be providedwith the low price.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows first embodiment of an air turbine handpiece according tothe present invention, and

FIGS. 1( a), (b) are a vertical cross-sectional view and across-sectional view showing the constitution of the reflux duct openedtoward the turbine room near at the air supply port,

FIG. 2 is an operational explanatory view of the reflux in the airturbine handpiece of the first embodiment,

FIG. 3 is a diagram showing the rotational speed and the power of therefluxed turbine-drive as for the exhaust in the air turbine handpieceof the first embodiment,

FIG. 4 is a diagram showing the reflux duct aperture and the power ofthe refluxed turbine-drive as for the exhaust in the air turbinehandpiece of the first embodiment,

FIG. 5 shows second embodiment of the air turbine handpiece according tothe present invention, and

FIGS. 5( a), (b) are a vertical cross-sectional view and across-sectional view showing the constitution of the reflux duct openedtoward the turbine room near at the air supply port,

FIG. 6 is an operational explanatory view of the reflux in the airturbine handpiece of the second embodiment,

FIG. 7 is a perspective view showing external appearance of the entireair turbine handpiece.

BEST MOOD FOR CARRYING THE PREFERRED EMBODIMENT

Even if inspired air for the drive is stopped to stop the drive of theair turbine handpiece, the object of preventing negative pressure frombeing generated in the turbine room by inertia rotation of the turbineblade, can be achieved with a simple constitution, by providing thereflux duct in such a manner that one end as reflux entry is opened tothe exhaust tube and the other end as reflux exit is opened to theturbine room near the air supply port of the air supply port. Moreover,the object that the rotation driving force of the handpiece isreinforced and energy-saving effect is attempted, can be achieved bysetting a value in which an aperture at the reflux exit of the refluxduct is divided by an aperture in the air supply port of the air supplyduct, becomes one or less (≧1).

First Embodiment

As shown in the FIG. 7, an air turbine handpiece 1 of this embodimentthat applies the present invention comprises a neck portion 2 grasped byan operator, a head portion 3 installed consecutively to the tip side ofthe neck portion 2, and a grip portion 4 installed consecutively behindthe neck portion 2, and a hose 5 with built-in feed pipe and exhaustpipe (not shown) is connected with the rear end of the grip portion 4.

As shown in FIG. 1, a turbine room 15 is formed in the interior of thehead portion 3 of the air turbine handpiece 1, and a turbine blade 6 isfixed to a chuck 8 that supports a tool 7, in interior of the turbineroom 15, and is rotatably supported by ball bearings 9 of one pair ofupper and lower sides through the chuck 8. Moreover, on the upper end ofthe chuck 8, the tool 7 is constructed detachably by compressing apushbutton 10 against energisation of a spring 10 a. Furthermore, at theside of the neck portion 2 of the head portion 3, an air supply line 11for rotating the turbine blade 6 and an exhaust duct 12 for exhaustingair after the turbine blade 6 is rotated, are provided, andadditionally, a nozzle 13 is installed consecutively to the exit side ofthe air supply line 11, so that air is jetted from an air supply port 14formed to the tip of the nozzle 13 toward a turbine room 15.

In this embodiment, a reflux duct 16 is installed consecutively to theexhaust duct 12 through a reflux entry 19 for exhausting, in the aboveconstitution, and a reflux exit 17 of the other end of the reflux duct16 is opened in the turbine room 15 near the air supply port 14 of theair supply line duct 11. According to the air turbine handpiece 1 of theabove constitution, in the case of stopping the air supply with the airsupply duct 11, as shown in FIG. 2 by an arrow (a), a part of exhaustflowed into the exhaust duct 12 flows from the reflux exit 17 into thearea A of the air supply port 14 in the turbine room 15 near through thereflux duct 16. The area A is a portion where the negative pressures aregenerated easily most when inspired air is stopped, by refluxing theexhaust in this area A directly, so that the negative pressure can beefficiently prevented from being generated. Furthermore, during theturbine-drive of the air turbine handpiece 1, supply air jetted from theair supply port 14, that is, the reflux exhaust in addition to thepressurizing charge flows into the turbine room 15 of the air supplyport near through the reflux duct 16, so that the air supply quantityincreases, and the rotation driving force of the turbine is reinforced.As a result, the energy-saving efficacy can be effected.

However, as to the reinforcement of the rotation driving force, thefollowings are examined; the explanation thereof is as follows. As anexample, in case that the diameter of the air supply port 14 in FIG. 1is made 1.3 mm, in the diagram showing FIGS. 3( a) to (g), in which thepower is taken as ordinates and the cycle is taken as abscissas, (a) isa case that reflux duct 16 is not installed, and the highest power 23.50W is shown by 200,000 rotations of the turbine. On the other hand,hereinafter, there is shown the relation between the highest power andthe cycle in the case that the reflux duct 16 was installed. 23.66 Wevery 220,000 rotations in (b). 25.91 W every 230,000 rotations in (c).27.48 W every 250,000 rotations in (d). 25.53 W every 240,000 rotationsin (e). 26.34 W every 240,000 rotations in (f). 23.44 W every 230,000rotations in (g). In each air turbine handpiece where the reflux ductdiameter was changed, the pressure in hand at the no-load running is setto 0.22 MPa (2.2 bar), so that the supply quantity of air is notconstant, and is a tendency to decrease. It could identify an effect towhich by installing the reflux duct 16 and returning the exhaust to theturbine room 15, the amount of the supply air increases, consequently,the cycle increases from 200,000 to 250,000 rotations, and as show by anarrow in FIG. 3, the power could be remarkably improved.

Moreover, in the case that the diameter of the air supply port 14 inFIG. 1 is made 1.3 mm, in the diagram shown in FIG. 4, in which thepower is took as ordinates and the diameter of 21 exit at the refluxduct is took as abscissas, the maximum work becomes 23.50 W in the airturbine handpiece 1 of the old model that do not form the reflux duct 16therein. It shows the effect that in the air turbine handpiece of thepresent application in which the reflux duct 16 is formed, the workbecomes a maximum which is 26.95 W, near the diameter 1 mm of the refluxexit 17 of the reflux duct 16, and the power increased remarkably. Onthe other hand, it shows the effect that in the air turbine handpiece ofthe present application in which the reflux duct 16 is formed, the workbecomes a maximum which is 26.95 W, near the diameter 1 mm of the refluxexit 17 of the reflux duct 16, and the power increased remarkably.

As is seen from the above-described result, as to the reflux exit 17 ofthe reflux duct 16, the effect is seen from 0.8 mm to 1.2 mm of thediameter relative to the diameter of 1.3 mm in the air supply port 14,and the effect shows a tendency to decrease gradually in the ranges of0.8 mm or less and 1.2 mm or more. Also, it turned out that the diameterof the air supply port is made preferably, 1.0 mm to 1.2 mm among 0.8 mmto 1.2 mm, most preferably, 1.0 mm.

Thus, in the case that the height of the turbine blade in the presentinvention is made 3 mm, and a diameter of air supply port is made 1.3mm, as a diameter of the reflux exit by which the rotation driving forceis efficiently enhanced, the reflux exit diameter is made 1.0 mm to 1.2mm, preferably, 1.0 mm. If this is represent by an aperture ratio, itbecame the most preferable result that a value in which an aperture ofthe reflux exit is divided by an aperture in the air supply port,becomes one or less, effectively 0.62-0.92, and 0.77 most preferably.

Moreover, if a diameter of the air supply aperture is made smaller than1.3 mm according to the capacity of the turbine room 15, it is commonknowledge in the same business that the rotating speed goes up too much.That is, if it is an aperture that the air supply of an extent whererotating speed of turbine blade 6 does not go up too much, that is, anextent where noise does not grow, becomes possible, the diameter of theair supply port cannot be limited to the above aperture thereof. Also,if the diameter of the air supply port is enlarged oppositely than 1.3mm oppositely, it has misgivings about that the rotating speed 300000rpm-400000 rpm, preferably, 350000 rpm-400000 rpm of the turbine blade6, cannot be obtained. However, in case that a constant flow rate(desired rotating speed) can be kept, even if diameter of the air supplyport is larger than 1.3 mm, the diameter of the air supply port cannotbe limited to the above aperture thereof.

Therefore, according to the air turbine handpiece of the presentinvention, in the case of stop of the air supply, the exhaust isreturned to the turbine room 15 nears the air supply port 14, and thusthe negative pressure can be efficiently prevented from being generatedin the turbine room. Moreover, during the turbine-drive, in addition tothe charge jetted from the air supply duct 11 to the turbine room 15,the exhaust is returned to the turbine room, so that the amount of theair supplied to the turbine room 15 increases, and the rotation drivingforce of turbine blade 6 is reinforced. As a result, the energy-savingefficiency can be affected. Moreover, the reflux of the exhaust in thecase of stop of turbine drive, is not limited to the above description,and can also be returned to the air supply port 14 nears. Also, thediameters of the air supply line 11 and the reflux duct 16 are notlimited to the above description. Also, the structure is simple and canalso be provided inexpensively.

Second Embodiment

FIG. 5 shows second embodiment of an air turbine handpiece of thepresent invention. As shown in FIGS. 5 (a) and (b), in an air turbinehandpiece 1 according to the present embodiment 2, is constructed insuch a manner that instead of the fact that the reflux exit 17 of thereflux duct 16 is opened to the air supply port 14 near the air supplyduct 11 in the above first embodiment, the reflux exit 21 of the refluxduct 20 communicated with the reflux entry 22 opened to the exhaust duct12, is opened to near the air supply port 14 in the nozzle 13 of the airsupply duct 11 near.

In this case, when the supply of air from the air supply duct 11 isstopped, as shown in FIG. 6 by an arrow (b), the exhaust air exhaustedby the inertia rotation of turbine blade 6 is entered in the nozzle 13from the reflux exit 21 through the reflux entry 22 of reflux duct 20,and is flowed to the area A of the turbine blade 6. As a result,although in the case of present embodiment, the operational advantagesimilar to above first embodiment can be effected. Furthermore, in caseof using the air turbine handpiece 1, the reflux exhaust flows into thenozzle 13, and is jetted into the turbine room 15 together with thepressurized charge, so that it will become help by which the refluxexhaust rotates and drives the turbine blade 6, and thus the secondaryadvantage can be effected.

According to the air turbine handpiece 1 of present embodiment 2, fromthe above, after the supply of the dissolved air from the air supplyduct 11 is stopped, the turbine blade 6 rotates through inertia, so thateven if the air in the turbine room 15 is sent into the exhaust port 18and the negative pressure starts being generated near in the air supplyport 14, this air flows into the area A being the negative pressuregeneration portion through the exhaust duct 16, and thus the negativepressure is canceled. Moreover, during use in the handpiece 1, thereflux air flows from the reflux duct 20 into the nozzle 13 of the airsupply duct 11, and flows into the turbine blade 6 together with thedissolved air, so that the negative pressure is canceled. Moreover,during use in the handpiece 1, the reflux air flows from the reflux duct20 into the nozzle 13 of the air supply duct 11, and jets toward theturbine blade 6 together with the dissolved air. As a result, thesecondary efficiency that the rotation of turbine blade 6 can be helpedcan be effected.

To explaining in full as to help of the rotation, the reflux duct 16 isformed more thinly than the nozzle 13 connected to the air supply duct11, and is opened to the interior of the nozzle 13 in the slopedirection along the direction of the airflow, so that the negativepressure is generated at the reflux exit 21 by the dissolved air passedthrough the interior of the nozzle 13 with high speed, and thus the airin the reflux duct 20 is drawn in the nozzle 13. As a result, therefluxed air is jetted from the air supply port 14, in addition to thesupplied and pressurized air, Moreover in the above description, in caseof stopping the supply of air, the exhaust only has to be returned nearsthe air supply port 14, so that the diameter of the reflux duct 20 andmounting angle to the nozzle are not limited to the above description.Therefore, the structure of the air turbine handpiece 1 according to thepresent invention is simple and can be provided inexpensively.

EXPLANATIONS OF LETTERS OR NUMERALS

1. Air turbine handpiece

2. Problem portion

3. Head portion

4. Grip portion

5. Hose

6. Turbine blade

7. Tool

8. Chuck

9. Ball bearing

10. Pushbutton

11. Air supply tube

12. Exhaust tube

13. Nozzle

14. Air supply port

15. Turbine room

16. Reflux duct line

17. Reflux exit

18. Exhaust vents

19. Reflux exit

20. Reflux entrance

21. Reflux exit

22. Reflux entrance

1. Air turbine handpiece comprising a head portion forming therein aturbine room, in which a rotatable turbine blade is provided; a neckportion installed consecutively with the head portion and grasped by anoperator; a grip portion installed consecutively with the neck portionbehind thereof; an air supply duct for charging air from an air supplyport to drive the turbine blade; and an exhaust duct for exhausting theair from the exhaust vent after rotating the turbine blade by thecharged air; wherein the exhaust duct is provided with a reflux duct forthe exhausting, one end of the reflux dust is opened to the exhaust dustas an reflux entry, and the other end of the reflux dust is opened tothe turbine dust as the exhaust exit.
 2. The air turbine handpiece asclaimed in claim 1, wherein the reflux duct is constituted in such amanner that a value in which an aperture at the reflux exit of thereflux duct is divided by an aperture in the air supply port of the airsupply duct, becomes one or less, and the reflux exit of the reflux ductis opened to the turbine room near the air supply port between the airsupply port and the exhaust exit.
 3. The air turbine handpiece asclaimed in claim 1, wherein the reflux duct is constituted in such amanner that when the aperture in the air supply port of the air supplyduct is assumed to be D0, and the aperture at the reflux exit is assumedto be D1, the aperture at the reflux exit of the reflux duct is set asD0:D1=1:0.62 to 0.92, and the reflux exit of the reflux duct is openedto the turbine room near the air supply port between the air supply portand the exhaust exit.
 4. The air turbine handpiece as claimed in claim3, wherein the reflux duct is constituted in such a manner that when theaperture in the air supply port of the air supply duct is assumed to beD0, and the aperture at the reflux exit is assumed to be D1, theaperture at the reflux exit of the reflux duct is set as D0:D1=1:0.77,and the reflux exit of the reflux duct is opened to the turbine roomnear the air supply port between the air supply port and the exhaustexit.
 5. The air turbine handpiece as claimed in claim 1, wherein thereflux duct is installed consecutively with another reflux duct throughthe reflux entrance for exhausting opened to the exhaust tube, and thereflux exit of the reflux duct is opened to the turbine room of the airsupply port near in the tip of the nozzle installed consecutively to theexit side of the air supply duct.
 6. An air turbine handpiece comprisinga head portion forming therein a turbine room, in which a rotatableturbine blade is provided; a neck portion installed consecutively withthe head portion and grasped by an operator; a grip portion installedconsecutively with the neck portion behind thereof; an air supply ductfor charging air from an air supply port to drive the turbine blade; andan exhaust duct for exhausting the air from the exhaust port afterrotating the turbine blade by the charged air; wherein the air supplyduct is installed consecutively with a nozzle, and the exhaust duct isprovided with a reflux duct, one end of the reflux duct is opened to theexhaust duct as an reflux entry, and the other end of the reflux duct isopened to near the air supply port of the nozzle as an exhaust exit.